234 WIEDEMANN ON THE MOTION OF LIQUIDS 



The author hopes, that, by the following experiments, he may 

 have succeeded in approaching somewhat nearer than has 

 hitherto been done, to the true nature of this phaenomenon, so 

 important to the whole science of the galvanic current. 



§2. 



In order partly to repeat former experiments, partly also to 

 investigate the general phaenomena connected with the trans- 

 porting action of the galvanic current, the author employed an 

 apparatus of very similar construction to the one generally used 

 for the decomposition of water. 



Two bottle-shaped glass vessels a a, (Plate IV. fig. 1), with double 

 necks c c^ and dd^, communicate with each other by means of a 

 wider aperture at b b, provided with a thick glass margin. The 



investigation of the electrolysis of secondary combinations {Vo^g. Ann. Ergan- 

 zungs, Bd. i. s. 569). From the facts there cited, it may be seen how little the 

 real cause of the phaenomenon has been approached. In order to complete the 

 literature on this subject, already cited by Poggendorff, the following may be 

 added. The fact of the transference of water through strata of sand or bladder 

 by means of a galvanic current, was discovered by Porrett in the year 1816, or 

 perhaps much earlier, in 1809, by Reuss, in Moscow (SeyfFer's Geschichtliche 

 Darstellung des Galvanismus, 1848, s. 542). In giving to it the name elec- 

 trical endosmose, it was immediately referred to an improper cause. The 

 subject received but little extension from the investigations of Becquerel and 

 Daniell, who, it must be admitted, did not submit the matter to direct investi- 

 gation. With the exception of the interesting observation made by Becquerel, 

 that in electrical endosmose particles of the porous diaphragm were sometimes 

 also transported with the current of liquid, the experiments of these two phy- 

 sicists confine themselves almost entirely to the proof that dilute sulphuric acid 

 does not follow the current, and that saline solutions in general manifest the 

 phaenomena in a higher degree than pure water (?). Lately the subject has 

 been further treated by Napier (Phil. Mag. July 1846). Napier distinguishes 

 visible and invisible electrical endosmose, inasmuch as the current may trans- 

 port liquids as well as the salts they contain in solution. He considers more 

 particularly the latter phaenomenon, which may be said to have a close con- 

 nexion with the secondary electrolytic phaenomena observed by Daniell and 

 others. To Napier, the visible endosmose was always most perceptible when, 

 in the saline solution, the salt was most decomposed ; it was also very visible 

 with distilled water. Lastly, it is possible that the interesting observations 

 of Armstrong (Phil. Mag. S. 3. vol. xxiii. p. 94, and Pogg. Ann. Bd. Ix. 

 8. 352), where, with a strong hydro-electrifying machine, a motion of distilled 

 water towards the part of the apparatus charged with negative electricity could 

 also be perceived, may be intimately connected with the phaenomena of the 

 transference of liquids in the galvanic circuit. 



